Cryoballoon Ablation as Initial Therapy for Atrial Fibrillation.

BACKGROUND: In patients with symptomatic paroxysmal atrial fibrillation that has not responded to medication, catheter ablation is more effective than antiarrhythmic drug therapy for maintaining sinus rhythm. However, the safety and efficacy of cryoballoon ablation as initial first-line therapy have not been established. METHODS: We performed a multicenter trial in which patients 18 to 80 years of age who had paroxysmal atrial fibrillation for which they had not previously received rhythm-control therapy were randomly assigned (1:1) to receive treatment with antiarrhythmic drugs (class I or III agents) or pulmonary vein isolation with a cryoballoon. Arrhythmia monitoring included 12-lead electrocardiography conducted at baseline and at 1, 3, 6, and 12 months; patient-activated telephone monitoring conducted weekly and when symptoms were present during months 3 through 12; and 24-hour ambulatory monitoring conducted at 6 and 12 months. The primary efficacy end point was treatment success (defined as freedom from initial failure of the procedure or atrial arrhythmia recurrence after a 90-day blanking period to allow recovery from the procedure or drug dose adjustment, evaluated in a Kaplan-Meier analysis). The primary safety end point was assessed in the ablation group only and was a composite of several procedure-related and cryoballoon system-related serious adverse events. RESULTS: Of the 203 participants who underwent randomization and received treatment, 104 underwent ablation, and 99 initially received drug therapy. In the ablation group, initial success of the procedure was achieved in 97% of patients. The Kaplan-Meier estimate of the percentage of patients with treatment success at 12 months was 74.6% (95% confidence interval [CI], 65.0 to 82.0) in the ablation group and 45.0% (95% CI, 34.6 to 54.7) in the drug-therapy group (P<0.001 by log-rank test). Two primary safety end-point events occurred in the ablation group (Kaplan-Meier estimate of the percentage of patients with an event within 12 months, 1.9%; 95% CI, 0.5 to 7.5). CONCLUSIONS: Cryoballoon ablation as initial therapy was superior to drug therapy for the prevention of atrial arrhythmia recurrence in patients with paroxysmal atrial fibrillation. Serious procedure-related adverse events were uncommon. (Supported by Medtronic; STOP AF First ClinicalTrials.gov number, NCT03118518.).

Quality of life after the initial treatment of atrial fibrillation with cryoablation versus drug therapy.

BACKGROUND: The STOP AF First trial recently demonstrated that initial treatment with cryoballoon ablation (CBA) is safe and superior to antiarrhythmic drug (AAD) therapy for preventing atrial arrhythmia recurrence in patients with symptomatic atrial fibrillation (AF). OBJECTIVE: The purpose of this study was to evaluate the change in quality of life (QoL) and symptoms after first-line CBA vs AAD therapy. METHODS: Patients with symptomatic AF not previously receiving rhythm control therapy were randomized to AAD (class I or III) or CBA (Arctic Front Advance, Medtronic, Mounds View, MN). QoL was evaluated at baseline and at 6 and 12 months by using the Atrial Fibrillation Effect on QualiTy-of-Life (AFEQT) and the European Quality of Life-5 Dimensions questionnaires. A review of AF-associated symptoms was conducted at baseline and at 1, 3, 6, and 12 months. RESULTS: In total, 203 subjects received either CBA (n = 104 [51.2%]) or AAD therapy (n = 99 [48.8%]). Improvements in the AFEQT summary and subscale scores were significantly larger with CBA than with AAD therapy at 6 and 12 months (P < .02 for all). Clinically meaningful improvement (>5 points) in the AFEQT summary score from baseline to 12 months was observed in 96.0% (100) of patients in the CBA arm vs 72.2% (71) of patients in the AAD arm (P < .001). No significant between-group differences were observed in the change in the European Quality of Life-5 Dimensions index or visual analog scale scores. Overall, 54.4% (57) of the CBA group vs 29.7% (29) of the AAD group reported no AF-specific symptom recurrence after a 90-day blanking period (P = .0005). CONCLUSION: First-line CBA vs AAD therapy is associated with larger improvements in AF-specific QoL and a higher rate of symptom resolution.

Biphasic versus monophasic shock waveform for conversion of atrial fibrillation: the results of an international randomized, double-blind multicenter trial.

OBJECTIVES: This study compared a biphasic waveform with a conventional monophasic waveform for cardioversion of atrial fibrillation (AF). BACKGROUND: Biphasic shock waveforms have been demonstrated to be superior to monophasic shocks for termination of ventricular fibrillation, but data regarding biphasic shocks for conversion of AF are still emerging. METHODS: In an international, multicenter, randomized, double-blind clinical trial, we compared the effectiveness of damped sine wave monophasic versus impedance-compensated truncated exponential biphasic shocks for the cardioversion of AF. Patients received up to five shocks, as necessary for conversion: 100 J, 150 J, 200 J, a fourth shock at maximum output for the initial waveform (200 J biphasic, 360 J monophasic) and a final cross-over shock at maximum output of the alternate waveform. RESULTS: Analysis included 107 monophasic and 96 biphasic patients. The success rate was higher for biphasic than for monophasic shocks at each of the three shared energy levels (100 J: 60% vs. 22%, p < 0.0001; 150 J: 77% vs. 44%, p < 0.0001; 200 J: 90% vs. 53%, p < 0.0001). Through four shocks, at a maximum of 200 J, biphasic performance was similar to monophasic performance at 360 J (91% vs. 85%, p = 0.29). Biphasic patients required fewer shocks (1.7 +/- 1.0 vs. 2.8 +/- 1.2, p < 0.0001) and lower total energy delivered (217 +/- 176 J vs. 548 +/- 331 J, p < 0.0001). The biphasic shock waveform was also associated with a lower frequency of dermal injury (17% vs. 41%, p < 0.0001). CONCLUSIONS: For the cardioversion of AF, a biphasic shock waveform has greater efficacy, requires fewer shocks and lower delivered energy, and results in less dermal injury than a monophasic shock waveform.

Fish oil supplementation and risk of ventricular tachycardia and ventricular fibrillation in patients with implantable defibrillators: a randomized controlled trial.

CONTEXT: Clinical studies of omega-3 polyunsaturated fatty acids (PUFAs) have shown a reduction in sudden cardiac death, suggesting that omega-3 PUFAs may have antiarrhythmic effects. OBJECTIVE: To determine whether omega-3 PUFAs have beneficial antiarrhythmic effects in patients with a history of sustained ventricular tachycardia (VT) or ventricular fibrillation (VF). DESIGN AND SETTING: Randomized, double-blind, placebo-controlled trial performed at 6 US medical centers with enrollment from February 1999 until January 2003. PATIENTS: Two hundred patients with an implantable cardioverter defibrillator (ICD) and a recent episode of sustained VT or VF. INTERVENTION: Patients were randomly assigned to receive fish oil, 1.8 g/d, 72% omega-3 PUFAs, or placebo and were followed up for a median of 718 days (range, 20-828 days). MAIN OUTCOME MEASURES: Time to first episode of ICD treatment for VT/VF, changes in red blood cell concentrations of omega-3 PUFAs, frequency of recurrent VT/VF events, and predetermined subgroup analyses. RESULTS: Patients randomized to receive fish oil had an increase in the mean percentage of omega-3 PUFAs in red blood cell membranes from 4.7% to 8.3% (P<.001), with no change observed in patients receiving placebo. At 6, 12, and 24 months, 46% (SE, 5%), 51% (5%), and 65% (5%) of patients randomized to receive fish oil had ICD therapy for VT/VF compared with 36% (5%), 41% (5%), and 59% (5%) for patients randomized to receive placebo (P = .19). In the subset of 133 patients whose qualifying arrhythmia was VT, 61% (SE, 6%), 66% (6%), and 79% (6%) of patients in the fish oil group had VT/VF at 6, 12, and 24 months compared with 37% (6%), 43% (6%), and 65% (6%) of patients in the control group (P = .007). Recurrent VT/VF events were more common in patients randomized to receive fish oil (P<.001). CONCLUSION: Among patients with a recent episode of sustained ventricular arrhythmia and an ICD, fish oil supplementation does not reduce the risk of VT/VF and may be proarrhythmic in some patients.

Prognostic value of baseline electrophysiology studies in patients with sustained ventricular tachyarrhythmia: the Antiarrhythmics Versus Implantable Defibrillators (AVID) trial.

OBJECTIVES: We sought to determine the value of electrophysiology (EP) testing in patients with ventricular fibrillation (VF), ventricular tachycardia (VT) with syncope, or sustained VT in the setting of left ventricular dysfunction. BACKGROUND: Traditionally, EP testing is part of the workup of patients with sustained VT or VF. Recently, some have suggested that EP testing is unnecessary in these patients, many of whom are likely to receive an implantable cardioverter-defibrillator (ICD). METHODS: Within a multicenter trial (Antiarrhythmics Versus Implantable Defibrillators) designed to evaluate whether drugs or ICD resulted in a better outcome, data were analyzed regarding EP testing. Although this testing was not required, it was performed in >50% of patients. Information regarding the results of EP testing was correlated to baseline clinical characteristics and outcome. RESULTS: Of 572 patients subjected to an EP test, 384 (67%) had inducible sustained VT or VF. Inducible patients were more likely to have coronary artery disease, previous infarction, and VT as their index arrhythmic event. Inducibility of VT or VF did not predict death or recurrent VT or VF. CONCLUSIONS: Information derived from EP testing in this patient population, particularly those with VF, is of limited value and may not be worth the risks and costs of the procedure, particularly in those patients likely to receive an ICD.

Nonautomatic focal atrial tachycardia: characterization and ablation of a poorly understood arrhythmia in 38 patients.

Nonautomatic focal atrial tachycardia (NAFAT) is a rare and poorly understood arrhythmia either due to microreentry or triggered mechanism. NAFAT was defined as a focal atrial tachycardia which was inducible with pacing maneuvers in the electrophysiology lab. We reviewed the charts and EP study reports of all 38 patients with NAFAT, who underwent an EP study at our center between April 1994 and September 2000. Patients' were predominantly female (n = 31, 82%), aged 11-78 years (median 46). The mean age at presentation was 31 years (range 7-71 years). None of the patients had structural heart disease or had undergone prior heart surgery. Electroanatomic mapping (EAM) was performed in 22 patients and showed no scars in the atrium. A total of 45 foci were identified (range 1-3 foci/patient). Anatomically NAFAT foci were predominantly right atrial (n = 35) rather than left (n = 10). The NAFAT cycle length ranged from 270 to 490 (mean +/- SD; 380 +/- 69 ms) and was significantly lower in patients younger than 24 years of age. Ablation, attempted for 42 foci was successful in 33 (79%). The success rate in the EAM group was 20/25 foci (80%) compared to 13/18 (72%) in the non-EAM group. In conclusion, NAFAT is a rare arrhythmia which predominantly affects women with no other associated cardiac disease. It mainly occurs in the right atrium, affects all ages and is amenable to catheter ablation.